Burner manifolds used in gas fired appliances, such as furnaces and boilers should be leak free in order to inhibit the uncontrolled escape of gas. Leaks in the burner system may result in inefficient combustion, undesirable fumes and possible gas ignition hazards.
Prior art constructions generally consist of a tube bent into a predetermined shape. In general, the shape is a function of the combustion chamber in which the manifold is mounted. Typically, one end of the tube includes a means for connecting to a control valve that controls the communication of a combustible gas to the tube. The opposite end of the tube is generally sealed. Gas communicated to the tube is generally discharged through apertures formed in the tube which may include burner nozzles. The gas discharged through the apertures/nozzles is burned to produce heat.
In prior art constructions, the end of the tube opposite the control valve is generally sealed using a friction welding technique. In general, this process involves mounting the tube in a chuck and spinning it at high speed while bringing a heat resistant bit in contact with the end. The contact between the bit and the end of the tube creates heat and bends the material inwardly ultimately forming a welded end seal.
Although the prior art process for sealing a tube is generally effective, it must be performed on a straight tube and before other processing steps, such as painting, punching, tapping and bending are performed. It has been found that at times it can be difficult to remove slugs from hole punching operations, chips from tapping operations and other dirt and debris from the tube once the one end is sealed. Moreover, washing of the tube prior to painting can also be difficult since with one end sealed, draining of the tube is inhibited, especially if the tube is bent prior to the washing/painting step.